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Date: Wed, 30 Aug 2017 19:52:02 +0000 (UTC)
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Subject: =?utf-8?Q?[jira]_[Commented]_(FLINK-6442)_Extend_TableAPI_Support?=
 =?utf-8?Q?_Sink_Table_Registration_and?=
 =?utf-8?Q?_=E2=80=98insert_into=E2=80=99_Clause_in_SQL?=
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archived-at: Wed, 30 Aug 2017 19:52:10 -0000


    [ https://issues.apache.org/jira/browse/FLINK-6442?page=3Dcom.atlassian=
.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D1614=
7920#comment-16147920 ]=20

ASF GitHub Bot commented on FLINK-6442:
---------------------------------------

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/3829#discussion_r136104550
 =20
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/t=
able/api/BatchTableEnvironment.scala ---
    @@ -106,6 +106,43 @@ abstract class BatchTableEnvironment(
       }
    =20
       /**
    +    * Registers an external [[TableSink]] in this [[TableEnvironment]]=
's catalog.
    +    * Registered sink tables can be referenced in SQL DML clause.
    +    *
    +    * Examples:
    +    *
    +    * - predefine a table sink with schema
    --- End diff --
   =20
    I think we should not require users to correctly configure the field na=
mes and types of the table sink before registering it.
    We can configure it ourselves:
   =20
    ```
    val tableSink: TableSink =3D ...
    val fieldNames: Array[String]  =3D Array("a", "b", "c")
    val fieldTypes: Array[TypeInformation[_]]  =3D Array(Types.INT, Types.L=
ONG, Types.STRING)
   =20
    tableEnv.registerTableSink("example_sink_table", fieldNames, fieldTypes=
, tableSink)
    ```


> Extend TableAPI Support Sink Table Registration and =E2=80=98insert into=
=E2=80=99 Clause in SQL
> -------------------------------------------------------------------------=
------
>
>                 Key: FLINK-6442
>                 URL: https://issues.apache.org/jira/browse/FLINK-6442
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table API & SQL
>            Reporter: lincoln.lee
>            Assignee: lincoln.lee
>            Priority: Minor
>
> Currently in TableAPI  there=E2=80=99s only registration method for sourc=
e table,  when we use SQL writing a streaming job, we should add additional=
 part for the sink, like TableAPI does:
> {code}
> val sqlQuery =3D "SELECT * FROM MyTable WHERE _1 =3D 3"
> val t =3D StreamTestData.getSmall3TupleDataStream(env)
> tEnv.registerDataStream("MyTable", t)
> // one way: invoke tableAPI=E2=80=99s writeToSink method directly
> val result =3D tEnv.sql(sqlQuery)
> result.writeToSink(new YourStreamSink)
> // another way: convert to datastream first and then invoke addSink=20
> val result =3D tEnv.sql(sqlQuery).toDataStream[Row]
> result.addSink(new StreamITCase.StringSink)
> {code}
> From the api we can see the sink table always be a derived table because =
its 'schema' is inferred from the result type of upstream query.
> Compare to traditional RDBMS which support DML syntax, a query with a tar=
get output could be written like this:
> {code}
> insert into table target_table_name
> [(column_name [ ,...n ])]
> query
> {code}
> The equivalent form of the example above is as follows:
> {code}
>     tEnv.registerTableSink("targetTable", new YourSink)
>     val sql =3D "INSERT INTO targetTable SELECT a, b, c FROM sourceTable"
>     val result =3D tEnv.sql(sql)
> {code}
> It is supported by Calcite=E2=80=99s grammar:=20
> {code}
>  insert:( INSERT | UPSERT ) INTO tablePrimary
>  [ '(' column [, column ]* ')' ]
>  query
> {code}
> I'd like to extend Flink TableAPI to support such feature.  see design do=
c: https://goo.gl/n3phK5


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